Solid state switches have been known heretofore. However, prior solid state switches have been constructed so as to limit operation of such switches to A.C. or D.C., respectively, and not providing for operation of the same switch on either A.C. or D.C. Also, such prior solid state switches have been handicapped in that the interface between the logic or control circuit of the switch and the power supply line was complex. It has also been known in the prior art that D.C. operation of a FET may be accomplished by a line-derived power supply as, for example, is illustrated by the circuit in FIG. 22, page A-47 of the 1982-83 International Rectifier HEXFET Data Book. Bi-directional A.C. switches have also been known heretofore as, for example, is illustrated in FIG. 5, page A-50, of the aforementioned Data Book. However, problems have been encountered in attempting to use the simple D.C. control power supplies with the A.C. switch. These attempts have led to complicated power supply schemes such as, for example, that shown in FIG. 6, page A-126, and FIG. 6, e A-129 of the aforementioned Data Book. Such problems have arisen due to the necessity of maintaining a minimum of 10 volts and a maximum of 20 volts gate-to-source in order to properly control the FETs; therefore, it has been necessary to provide transformer coupled power supplies to prevent such 20 volt maximum from being exceeded which, if allowed to occur, might render the circuit inoperative.